Filling joints with compound, especially in room corners is a difficult operation and over the years, a number of products have been developed to address this issue.
There are two categories of tools: The simple tools which have been used for years and were probably never patented and there are more complex tools which are themselves subdivided into two categories: Those that provide for a clean, even spreading of the joint filling compound and those that do that but with the added convenience of pushing the joint filling compound which is contained in a container that forms an internal part of the device.
Such combined devices have the drawback of either being very good at dispensing joint filler and not very good at applying it or very good at applying but not reliable in providing a steady supply of joint filling compound.
For example, U.S. Pat. No. 3,932,101 has a wheel that tend to clog up with compound and becomes quite inefficient over time. Other systems such as U.S. Pat. Nos. 2,59,4606 and 2,824,443 and 3,932,101 have openings which do not provide for even distribution of compound material. Generally, because of the shape of the devices gliding motion along a wall is not smooth and regular.